The present disclosures relate generally to MPEG video streams and more particularly, to dynamic determination of frames required to build a complete picture in an MPEG video stream.
MPEG is short for Moving Picture Experts Group, a working group of the International Standards Organization, and also refers to a family of digital video compression standards and file formats developed by the group. MPEG generally produces better-quality video than competing formats. In addition, MPEG files can be decoded by special hardware or by software.
In MPEG video streams, video data is reordered to assist in removing temporal similarities and thus increasing compression in the data stream. While this compression helps with, and is designed to allow for, forward play of the stream, difficulties arise when trying to play the stream in reverse order or start the stream at a random location in the stream. In particular, this issue arises in the context of Personal Video Recorder (PVR) applications. A PVR system must be able to stop the stream, advance slowly or quickly, and play the MPEG stream in reverse. For all of these play-back operations, the ability to build the pictures accurately is required, and thus all of the dependencies within the video stream are required.
Most PVR solutions today solve these problems in very brute force, computationally intensive ways. For example, one known solution includes reversing several frames and forcing that stream into the video decoder, hopefully coming up with a reasonable stream.
Accordingly, it would be desirable to provide an improved method for determination of frames required to build a complete picture in an MPEG video stream for overcoming the problems in the art.
The use of the same reference symbols in different drawings indicates similar or identical items. Skilled artisans will also appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention.